1951 R25/2 transmission mystery

[sp838]

Hello all. Please pardon me for posting in English.

I'm in the midst of a complete nuts and bolts restoration of a 1951 R25/2. The bike was by my estimates not a civilian market bike as, when I stripped it down, it had original olive drab paint that had been painted over. My guess is that it was a Forestry or Border Patrol bike in Germany before being imported to the US. The insides of the bike have revealed some mysteries, including the cylinder head with no oiling lines to the rocker arms, among other things... It definitely had a tough life.

Anyway, the reason for this post is because I am now rebuilding the transmission. The bike is a four speed, as we all know... However, the gear shift selector plate has six position notches in it. Why the extra notch? There should only be five, right? 1 - N - 2 - 3 - 4 should mean only five positions. To add to the consternation, the extra notch appears to be between 3rd and 4th gears. It produces a neutral state, where the input and output shafts can spin freely from each other.

As far as I know, the transmission was never opened up, at least not since it came into the family (my dad bought it used on the NYC grey market back in the mid 1960s.) To add to the mystery, old parts diagram drawings clearly show the plate with six notches in it. But on the updated parts microfiche images from BMW dealerships, the drawing only shows five...

Can anyone explain this to me? I'd really appreciate any insights or explanations. The rebuilt trans otherwise shifts well through all the gears, the dogs are aligned well in the middle of the grooved rings on the output shaft, new springs and bearings installed. I just want to know more about this before sealing it all up with the case cover.

Attached is a photo of my parts, and also the original parts drawing.

Thanks everyone!

[sp838]

[rolf]

it is a "mini neutral" between 3. and 4.....by this gearboxes you have to go out of the 3......then go into the 4.....by modern gearboxes you go from the 3. directly in the 4.

[sp838]

Thank you Rolf for your answer. Why is it designed this why? Is this "mini neutral" present in all the four speed gearboxes? It seems dangerous to me! Especially if downshifting...

[bwprice100]

Could it be a throw back to the hand shifter days when getting to a neutral quicker was desirable?

Hence the saying 'What do you mean you only have one neutral' .


www.eBolt.co.uk www.TooolroomChucks.co.uk

[sp838]

"Hence the saying 'What do you mean you only have one neutral' ."

lol I've never heard that saying...